The present invention relates to a method of fabricating semiconductor devices, and more specifically, to a method of forming gate electrode patterns of a semiconductor device.
As the level of integration of semiconductor devices increases, a gate electrode technique of a polycide/polysilicon/silicide structure using a refractory metal element such as tungsten has emerged. The gate electrode of the polycide structure is the limiting factor to the improvements of the operating speed of an ultra-high integrated semiconductor device. In view of the above, there has recently been active research in techniques using a refractory metal such as tungsten as the gate electrode.
In a subsequent oxidization ambient process, however, a refractory metal such as tungsten is exposed, and abnormal oxidization such as tungsten oxide (WO3) is generated at the sidewalls of refractory metals, resulting in a damaged profile of the gate electrode. It becomes an obstacle to obtaining desired device characteristics since the damaged profile of the gate electrode influences subsequent processes.
Furthermore, if refractory metals such as tungsten are severely oxidized, the amount of refractory metal is reduced. This presents the problem that resistance of the gate electrode is increased.
Accordingly, there is a need for techniques for solving problems which may be generated when refractory metal such as tungsten are used in a gate electrode.